Chalcopyrite (sometimes also referred to as chalcogenide and abbreviated to CIS) semiconductors are known in the art. They have the general formula Cu(In,Ga)(Se,S)2 and are used in thin film approaches for manufacturing solar cells. In these solar cells the chalcopyrite semiconductors acts as absorber layers for polycrystalline thin film solar cells. In these approaches the substrate of the entire module is coated with the required layers. Then the individual cells are dimensioned e.g. using a laser. Although the efficiency of these thin film solar cells having a CIS semiconductor is high compared to amorphous silicon based thin film solar cells, the costs are also high, which makes them less attractive.
Attempts have been made to manufacture a flexible solar cell using a metal e.g. a copper or brass substrate. A copper or brass substrate is expensive. Furthermore diffusion of copper atoms from the copper or brass substrate into the semiconductive layer could affect the performance of the solar cell. Therefore a diffusion barrier layer is electroplated on the metal substrate. Because the diffusion barrier is an electrical insulator, this requires a conductive contacting layer from specific metals and/or alloys to be applied on top of the diffusion barrier layer, as described in WO 01/57932. Additionally electroplating of both diffusion barrier and contacting layers makes the manufacturing process complex and expensive.
WO 2005/096395 discloses a coated metal substrate for a photovoltaic cell, wherein the coating comprises an essentially pore free layer of metallic molybdenum or molybdenum alloy that has been applied by a physical vapour deposition process.
It has also been observed that there is a risk of detachment of the semiconductor from the metal substrate substantially deteriorating the lifetime of the device.
Consequently, there is a general need for a flexible CIS based solar cell having improved properties with respect to stability and total efficiency. In addition, there is a need to provide a relative cheap and simple manufacturing process.